Iron vaporization chamber coating

ABSTRACT

A cladding in a vaporization chamber of an iron, the cladding being composed of a first layer composed essentially of sodium silicate, and at least locally a second layer composed of a fiber mat or a hydrophilic fabric, wherein the cladding has a surface treated with a treatment product containing phosphorus and having an acid group.

The present invention concerns steam irons.

These irons conventionally have a soleplate composed of a body generallymade of cast aluminum, and a cap covering the lower part of the body andcoming into contact with the items to be ironed. The body of thesoleplate generally of aluminum comprises a heating element, a chamberfor quasi-instantaneous vaporization of water and channels fordistribution of the steam produced toward steam orifices directed ontothe items through the cap.

The body of the soleplate must assure vaporization of the water as wellas temperature maintenance of the cap.

The boiling temperature of water being constant in the vicinity ofatmospheric pressure, the temperature of the wetted heating surface ofan evaporator only varies with the vaporization power and thus the vaporflow rate. This surface temperature varies only slightly around 110-130°C. Conversely, the temperature of the heating body of the soleplate canbe regulated depending on the fabrics over a range of the order of 80°C. to 200° C.

The vaporization chamber is coated on its wetted faces with a layer of ahydrophilic cladding having a low thermal conductivity which permits thewetted surface to remain at a temperature compatible with a goodvaporization without calefaction, regardless of the temperature of theheating body, the extent of the wetted surface being adjusted with theflow rate of the water and the thermal flux.

There is known the patent FR 2696197 in which this spreading of waterand wetting are aided. The cladding of the chamber is a silicate onwhich is placed a mat of fibers or a fabric retained by a grid that isable itself to be coated. The fibers have the advantage of increasingthe specific surface of the wetted region while completing the thermalinsulation, of storing and of distributing the water onto the surface ofthe chamber before it is vaporized.

Similarly, the patent FR 2707732 is known in which there is described avaporization chamber the bottom of which is constituted by hydrophilicfibers partially embedded in the material constituting the heating bodyof the soleplate.

However, the cladding mainly composed of a silicate is sensitive tocontamination and has a limited useful life. Moreover, the wettabilityof the fibers is generally obtained by removal of the oiling, whichactivates their surface but causes them to be susceptible to variousforms of contamination, so that the problems of failure to vaporize canbe periodically produced, characterized by an absence of wettability ofthe cladding, resulting in noise and sputtering of water through thevaporization holes of the soleplate.

It is known for example from the article “ceramics from A to Z” [laceramique de A à Z], which appeared in 1977 in the periodical “CeramicIndustry” [L'Industrie Céramique] that phosphorous salts such asaluminum phosphate yield with silica compounds that are difficult towash away. The patent EP 0425043 utilizes these properties to improvethe deposition in steam iron vaporization chambers by starting from asolution of colloidal silica. But this patent does not suggest the useof sodium silicate as a base product for the deposition, silicate havingthe advantage of cleaning and pickling the surface of aluminum ontowhich is applied, while saponifying the fatty material that may bepresent, which simplifies that application process and permits a goodanchoring of the following layers.

The patent FR 2522318 cites another property of phosphates, inparticular sodium tripolyphosphate, which, solubilized in the water tobe vaporized, impedes scaling up of the iron. Similarly, the patent FR2757364 cites the utilization of sodium hexametaphosphate in the waterto be vaporized in order to prevent scale from being deposited in amanner to form a crust in the iron. But these patents do not sayanything with regard to improvement of the wettability of thevaporization chamber, and the cited products remain soluble.

It is equally known that phosphorous products of the organic type alsohave anti-scaling properties and equally properties of stabilization ofemulsions having very low concentration.

The invention described hereafter has for its object a cladding of avaporization chamber for an iron improved in order to increase theuseful life of the cladding, having a reduced susceptibility tocontaminations as well as to scaling, and an excellent vaporizationperformance.

The object of the invention is achieved by a cladding of a vaporizationchamber of an iron, this cladding initially having a layer composedessentially of sodium silicate, and at least locally a fiber mat or ahydrophilic fabric, noteworthy in that the initial cladding has receiveda surface treatment with a product containing phosphorus and having anacid group.

The phosphorous product reacts with the silicate in neutralizing thesodium and is bound with the remaining silica in order to constitute abody that is difficult to wash away. The reaction although incompletelyanalyzed is produced at the surface of the silicate deposit andpreserves the attachment of the layer onto the support. The surfacebecomes chemically more neutral attaining a hydrogen potential (pH) ofthe order of 7 at the surface, which preserves it from accidentalcontaminations. The presence of the phosphorus permits an exceptionalwettability to be obtained when hot, this including on the fibers thatcannot be silicated, and the presence of these fibers permits aspreading of the water to be vaporized on a large surface, thusimproving performance. The fibers thus permit retention of a greaterquantity of the product issuing from the treatment.

Moreover, one notes that the deposits of tartar are less adherent tosuch a cladding.

Several phosphorous bodies are suitable for the treatment. One canutilize aluminum triphosphate for example, but,

Preferably the treatment product is a phosphonate for examplephosphonic-trimethylene-amino acid in solution in water.

With respect to the utilization of inorganic products and with equalresult the utilization of phosphonates is advantageous because itsuffices to have a maximum quantity by weight that is ten times less.The process and the installations for pollution control that can beassociated therewith are simplified.

Advantageously, the treatment product has an addition product such as asodium molybdate, a diacetate of molybdenum, a chloride of calcium or ofmagnesium aiding the bonding of the deposited layers.

This complementary product assures a better cohesion of the treatedsurface.

Advantageously the treatment product contains colloidal silica.

The layer of silicate is found to be reinforced thereby and the fibersbetter coated.

Advantageously, the cladding is obtained by evaporation of a solution ofthe treatment product in the chamber preliminarily coated with sodiumsilicate and at least locally with fibers.

This solution permits a good distribution of the treatment product and agood reaction with the initial cladding.

The invention will be better understood from a reading of the examplebelow and from the attached drawing.

FIG. 1 is a view in longitudinal cross section in a vertical plane of asteam iron soleplate having a coated vaporization chamber, the soleplatebeing horizontal. Only the initial cladding of the chamber isrepresented.

In a preferred version of the invention, a steam iron has a soleplatecomposed of a cap 1 constituting the ironing surface, a heating body 2of aluminum and in thermal connection with this cap. The heating bodycomprises a heating element 6 and a chamber 3 for the vaporization ofwater coming from a droplet source positioned on an opening 4 of theclosing plate 5 of the steam chamber.

The cladding of vaporization chamber 3 is composed of an initialcladding on which, according to the invention, is applied a treatmentproduct increasing the vaporization performance of the chamber.

The initial cladding of vaporization chamber 3 has a layer 10 of sodiumsilicate adhering strongly to the wall of heating body 2 of aluminum. Onthis layer is deposited a fabric 11 of glass fibers from which theoiling has been removed after fabrication. A grid 12 maintained byrivets 13 emanating from heating body 2 fixes the fabric of fibers 11.Fabric 11 covers at least the part of chamber 2 that receives the dropsof water, in line with opening 4 of closing plate 5.

In another version, fabric 11 is fixed on heating body 2 by grid 12. Thesilicate, then deposited, impregnates fabric 11.

In a preferred version, silicate layer 10 is reinforced by evaporationof a solution of colloidal silica in vaporization chamber 3.

According to a preferred version of the invention the treatment productis a solution in water of a phosphonic acid such asphosphonic-trimethylene-amino acid. This product is spread out insolution on the initial cladding at a rate of around two micrograms persquare centimeter of cladding surface then the solution reacting withthe initial cladding is evaporated.

Advantageously, the treatment product has a bonding element such assodium molybdate, and possibly a reinforcing agent such as colloidalsilica.

According to a practical form of construction of the invention, asolution of silicate is evaporated in vaporization chamber 3, then aftercooling, glass fabric 11 is fixed with grid 12 in order to obtain theinitial cladding, then 15 ml of a solution of 3% of silica and 0.3% ofphosphonate is evaporated in the vaporization chamber and the finalcladding is obtained, the indicative values cited corresponding to 25square centimeters of chamber surface.

The initial cladding of a known type has good adherence to the wall ofheating body 2. This initial cladding is affected at the surface by thetreatment, but the bonding in depth with support 2 is not affected,which gives the cladding according to the invention a good adherence.Neutralization of the basic surface of the initial cladding reduces thesensitivity of the cladding according to the invention to variouscontaminations and the presence of phosphorus gives it very usefulcharacteristics of wettability when hot.

What is claimed is:
 1. A cladding in a vaporization chamber of an iron,said cladding comprising a first layer composed essentially of sodiumsilicate, and at least locally a second layer composed of a fiber mat ora hydrophilic fabric, wherein said cladding has a surface treated with atreatment product containing phosphorus and having an acid group.
 2. Thecladding according to claim 1 wherein said first and second layers arebonded together, and the treatment product has an addition productselected from a sodium molybdate, a diacetate of molybdenum, and achloride of calcium or of magnesium aiding the bonding of said first andsecond layers.
 3. The cladding according to claim 1 wherein thetreatment product contains colloidal silica.
 4. The cladding accordingto claim 1 wherein the cladding is obtained by evaporation of a solutionof the treatment product in the chamber preliminarily coated with sodiumsilicate and at least locally with fibers.
 5. The cladding according toclaim 1 wherein the treatment product is a phosphonate in solution inwater.
 6. The cladding according to claim 5 wherein the phosponate isphosphonic-trimethylene-amino acid.
 7. The cladding according to claim 5wherein the treatment product contains colloidal silica.
 8. The claddingaccording to claim 5 wherein the cladding is obtained by evaporation ofa solution of the treatment product in the chamber preliminarily coatedwith sodium silicate and at least locally with fibers.
 9. The claddingaccording to claim 5 wherein said first and second layers are bondedtogether, and the treatment product has an addition product selectedfrom a sodium molybdate, a diacetate of molybdenum, and a chloride ofcalcium or of magnesium aiding the bonding of said first and secondlayers.
 10. The cladding according to claim 9 wherein the cladding isobtained by evaporation of a solution of the treatment product in thechamber preliminarily coated with sodium silicate and at least locallywith fibers.
 11. The cladding according to claim 9 wherein the treatmentproduct contains colloidal silica.
 12. The cladding according to claim11 wherein the cladding is obtained by evaporation of a solution of thetreatment product in the chamber preliminarily coated with sodiumsilicate and at least locally with fibers.
 13. A vaporization chamber ofan iron and a cladding on at least a portion of a surface of saidvaporization chamber, wherein said cladding is formed by: providing alayer composed essentially of sodium silicate and at least locally afiber mat or a hydrophilic fabric; and treating the surface of saidcladding with a treatment product containing phosphorus and having anacid group.